Piston pump

ABSTRACT

A piston pump, having at least one delivery plunger to deliver pressure fluid from a suction chamber via a working chamber into a pressure port, is provided with elastic damping elements arranged in the suction chamber to compensate for the occurring pressure pulsations.

BACKGROUND OF THE INVENTION

The present invention relates to a piston pump having at least onedelivery plunger delivering pressure fluid from a suction chamber via aworking chamber into a pressure port. Undesirable noises are caused bypressure pulsation in such pumps. For noise reduction, it is known fromDE AS 28 24 239 to direct the pressure fluid from the working chamber tothe pressure port via a collecting chamber which acts as a vibrationdamper.

To attenuate vibrations in the suction lines, it is known to useso-called "intake air vessels". However, these intake air vessels bearthe shortcoming of necessitating an enormous overall size in order tosafeguard an acceptable balance between the flow speed of the suctionfluid and the delivered fluid. Furthermore, they become ineffective inthe event of high-vacuum venting with subsequent pressure loading.

SUMMARY OF THE INVENTION

Therefore, the instant invention has for its object to accomplish noiseattenuation for piston pumps. The invention is characterized by smallspace requirements, while having optimum damping abilities. Theinvention is accomplished by simple means at low costs and lends itselfto ease of maintenance. The invention is suitable for use on pumps whichare vacuum-vented prior to pressure loading.

This object is achieved, according to the present invention, byarranging elastic damping elements in the suction chamber. In this way,the pressure vibrations in the suction area of the pump are compensateddirectly where they are caused.

A preferred embodiment of this invention provides an elastic dampingelement that is formed by at least one deformable shaped part whichcontains at least one closed gas-filled compartment. In a particularlyeconomical embodiment of this invention, the deformable shaped part ismade of closed-cell foam material or rubber. In this way, the elasticmeans can be easily adapted to the existing suction chamber geometry.

Another embodiment of this invention provides an elastic damping elementthat is a movable wall which confines a gas chamber within the suctionchamber. Thus, for instance, mounting of a diaphragm into the suctionarea permits effective noise attenuation in a simple fashion.

Another advisable embodiment of this invention arranges the dampingelement as an annularly closed rubber hose. This provides a largedamping surface, and the damping element can be easily inserted and heldin the suction chamber. For guiding purposes and for obtaining a defineddeformability, the damping element cooperates with the ring filterelement. The filter element is furnished with web-like retaining armswhich receive the damping element partially embracing it at a radialdistance. The webs are almost evenly spaced from each other, and thewall confining the suction chamber contributes to securing the dampingelement in position. This ensures ease of assembly, disassembly andquick exchangeability.

Further advantageous features, as well as the function of thisinvention, can be understood from the following description withreference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings

FIG. 1 shows the principal structure of a first embodiment of thisinvention,

FIG. 2 shows the design of a second embodiment of this invention,

FIG. 3 is a specific embodiment according to FIG. 1,

FIG. 4 is a full view of the damping element designed as a damping hosewith connecting portions shown in partial cross-section; and

FIG. 5 is a cross-sectional view of the radial piston pump of FIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 5 depicts schematically a radial piston pump 1 flanged to anelectric motor 2. This radial piston pump 1 delivers fluid out of areservoir into the pressure line 5 via the suction chamber 3 and thesuction line 4.

To compensate for pulsation of the suction pressure, an elasticallydeformable shaped part 6 is arranged in the suction chamber 3 which iscomposed of foam material with closed air bubbles or gas bubbles. Thegeometry of this shaped part 6 is dictated by the special spaceconditions in the suction area of the pump. In lieu of any foammaterial, a shaped part can also be used which, instead of a pluralityof bubbles, comprises only one or more specially shaped air compartmentsor gas compartments.

The embodiment shown in FIG. 2 provides a diaphragm 7 as an elasticmeans in the suction chamber 3. The diaphragm forms a closed compartment8 in the suction chamber 3, that is preferably filled with air. Thecompressibility of the air permits compensation for suction pressurepulsations.

The inventive embodiment illustrated in FIG. 3 shows an annularlyextending damping hose 9 arranged in the suction chamber 3. The dampinghose 9 is fixed by the annular filter element 10 arranged in the suctionchamber 3. To this end, the filter element 10 is furnished with severalretaining arms 11 distributed over the periphery of the filter elementpartially encompassing the damping hose 9, thereby clamping it betweenthe filter element 10 and the adjoining wall in the housing 12. Thedamping hose 9 is designed as a component part assembled at its twoends, or it can be composed of several segments which are put together.

FIG. 4 shows a full view of the gas-filled damping hose 9. In the areaof the partial cross-section, the obtuse-angularly bent connectingportion 13 is fitted into the two ends of the hose to close thegas-impermeable compartment 8 in the damping hose 9 in a pressure-fluidtight manner. Preferably, the damping hose 9 is made of rubber so thatthe preloading force of the expanded rubber holds the two hose endscaptive on the connecting portion 13 which is chamfered like a truncatedcone on both sides.

What is claimed is:
 1. A piston pump having at least one deliveryplunger delivering pressure fluid from a suction chamber via a workingchamber into a pressure port, characterized in that at least oneelastomeric damping element is arranged in said suction chamber, andthat a filter element has several substantially axially extendingretaining arms spread over a periphery of said filter element tocooperate with an external diameter of said at least one elastomericdamping element.
 2. A piston pump as claimed in claim 1, characterisedin that the elastomeric damping element is formed by at least onedeformable shaped part (6, 9) which contains at least one closedgas-filled compartment.
 3. A piston pump as claimed in claim 1,characterised in that the elastomeric damping element is a damping hose(9) of a preferably annular, closed configuration.
 4. A piston pump asclaimed in claim 3, characterised in that the damping hose (9) has anannular profiled cross-section.
 5. A piston pump as claimed in claim 3,characterised in that the damping hose (9) comprises a compartment (8)filled with gas.
 6. A piston pump as claimed in claim 5, characterisedin that the compartment (8) is closable pressure-fluid-tightly by aconnecting portion (13) which is insertable into the two ends of thedamping hose (9).
 7. A piston pump as claimed in claim 6, characterisedin that the connecting portion (13) of the damping hose (9) has acircular cross-section and is bent preferably in an obtuse-angledmanner.
 8. A piston pump as claimed in claim 6, characterised in thatthe external diameter of the connecting portion (13) is larger than theinternal diameter of the damping hose (9) mirror-symmetrically by anidentical length to be inserted into the damping hose (9) on either sideof its angled-off portion.
 9. A piston pump as claimed in claim 6,characterised in that the external diameter of the connecting portion(13) by approximation corresponds to the external diameter of thedamping hose (9).
 10. A piston pump having at least one delivery plungerdelivering pressure fluid from a suction chamber via a working chamberinto a pressure port, characterized in that at least one elastomericdamping element is arranged in the suction chamber, that the elastomericdamping element is a damping hose of an annular, closed configuration,and that the external diameter of the damping hose cooperates withseveral substantially axially extending retaining arms which are spreadover the periphery of a filter element.
 11. A piston pump as claimed inclaim 10, characterised in that the retaining arms (11) of the filterelement (10) embrace the damping hose (9) partly radially.
 12. A pistonpump as claimed in claim 10, characterised in that the filter element(10) cooperates with the damping hose (9) in the suction chamber (3) ofthe pump.
 13. A piston pump as claimed in claim 10, characterised inthat the filter element (10) is conformed to the shape of the dampinghose and can be radially penetrated by fluid.
 14. A piston pump asclaimed in claim 3, characterised in that the damping hose (9), at itsperiphery, is in partially supporting contact with a wall confining thesuction chamber (3).